Stack, Alertdialogs und ScaffoldMessenger

main.dart

import 'package:flutter/material.dart';

void main() => runApp(const SnackbarDialogDemoApp());

class SnackbarDialogDemoApp extends StatelessWidget {
  const SnackbarDialogDemoApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'SnackBars & AlertDialogs Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        useMaterial3: true,
        colorSchemeSeed: Colors.redAccent,
      ),
      home: const HomeScreen(),
    );
  }
}

class HomeScreen extends StatelessWidget {
  const HomeScreen({super.key});

  void _showSimpleSnackBar(BuildContext context) {
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(
        showCloseIcon: true,
        content: Text('Hello! 👋 This is a simple SnackBar.'),
        duration: Duration(seconds: 10),
      ),
    );
  }

  void _showSnackBarWithAction(BuildContext context) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        backgroundColor: Colors.green,
        content: const Text('File deleted'),
        action: SnackBarAction(
          label: 'UNDO',
          onPressed: () {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(content: Text('Undo successful ✅')),
            );
          },
        ),
      ),
    );
  }

  Future<void> _showBasicDialog(BuildContext context) async {
    await showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Basic Dialog'),
        content: const Text('This is a simple AlertDialog message.'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('Close'),
          ),
        ],
      ),
    );
  }

  Future<void> _showConfirmDialog(BuildContext context) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Delete item?'),
        content: const Text('This action cannot be undone. Continue?'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('Cancel'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(context, true),
            child: const Text('Delete'),
          ),
        ],
      ),
    );

    if (confirmed == true) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Item deleted 🗑️')),
      );
    } else if (confirmed == false) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Action canceled ❌')),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('SnackBars & AlertDialogs')),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: ListView(
          children: [
            const Text(
              '🧩 SnackBar Examples',
              style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
            ),
            const SizedBox(height: 12),
            FilledButton.icon(
              onPressed: () => _showSimpleSnackBar(context),
              icon: const Icon(Icons.message),
              label: const Text('Show Simple SnackBar'),
            ),
            const SizedBox(height: 8),
            FilledButton.icon(
              onPressed: () => _showSnackBarWithAction(context),
              icon: const Icon(Icons.undo),
              label: const Text('Show SnackBar with UNDO Action'),
            ),
            const Divider(height: 32),
            const Text(
              '💬 AlertDialog Examples',
              style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
            ),
            const SizedBox(height: 12),
            FilledButton.icon(
              onPressed: () => _showBasicDialog(context),
              icon: const Icon(Icons.info_outline),
              label: const Text('Show Basic Dialog'),
            ),
            const SizedBox(height: 8),
            FilledButton.icon(
              onPressed: () => _showConfirmDialog(context),
              icon: const Icon(Icons.delete_outline),
              label: const Text('Show Confirmation Dialog'),
            ),
          ],
        ),
      ),
    );
  }
}

stack.dart

import 'package:flutter/material.dart';

void main() => runApp(const StackDemoApp());

class StackDemoApp extends StatelessWidget {
  const StackDemoApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Stack Example',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(useMaterial3: true, colorSchemeSeed: Colors.indigo),
      home: const StackExample(),
    );
  }
}

class StackExample extends StatelessWidget {
  const StackExample({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
          child: ListView(
        children: [
          Text("Tasd"),
          Text("Tasd"),
          SizedBox(
            height: 2000,
          ),
          Stack(
            alignment: Alignment.center,
            children: [
              Container(
                width: 250,
                height: 250,
                color: Colors.blue.shade100,
              ),
              Container(
                width: 150,
                height: 150,
                decoration: BoxDecoration(
                  color: Colors.indigo.shade300,
                  shape: BoxShape.circle,
                ),
              ),
              const Text(
                'Stack Example',
                style: TextStyle(
                  fontSize: 20,
                  fontWeight: FontWeight.bold,
                  color: Colors.white,
                ),
              ),
              Positioned.fill(
                child: Container(
                  color: Colors.red,
                  child: Text("data"),
                ),
              ),
            ],
          ),
        ],
      )),
    );
  }
}